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Re: HYB: breeding strategies
  • Subject: Re: HYB: breeding strategies
  • From: Linda Mann <lmann@lock-net.com>
  • Date: Mon, 31 Oct 2011 08:39:47 -0400

:-)  or maybe that should be ;-(

I appreciate your and Betty's thoughts on this. Yes, it's all abstract, but I've been so submerged in the specifics of trying to figure out possibilities and probabilities, that I haven't really been thinking as much about some of the generalities. As I'm potting up the seeds that have been in the fridge stratifying, I've been thinking more about what you've said about line and back-crosses, realizing that some/many of these crosses really aren't particularly likely to move me towards my goals.

One of the frustrations about breeding for rebloom (at least for me, and I think for others too), is that it seems like the probability for 'summer'/recessive rebloom [in my growing conditions] <ought> to be very high in a cross between two 'summer's (Betty's (1) type cross), but in reality, it's very low. There are a lot of other growth? traits that have to be present along with the summer/recessive rebloom trait, and thinking about it now, it seems 'obvious' that a better way to put together those packages of traits is in back crosses or line breeding.

Last year is the first time I made a bunch of back crosses to IMM. I didn't want to do it, because it is going backwards in form, plus getting more doses of genes that will give me a bunch of white flowers with no way other than test crosses to get back to any kind of interesting color and pattern.

On the other hand, Betty's 'kitchen sink' approach can also work - it's the approach I've been working towards. And that approach allows more following of color, pattern, and form than backcrosses and line breeding can allow at this stage of my breeding program.

It's not always a
simple matter to make a connection between what we read about breeding and
the realities of figuring out what to do with a batch of seedlings that
aren't what we expected.

So far, it's mostly been a vague hope that this might happen, but the best fertility/opportunities haven't been very modern parents. But I will keep occasionally working the best oncers descended from IMM with an occasional back cross. Another 10 yrs should do it. I will still be in my 70s, so maybe my wits will still be working enough to do this.

If you were
trying to combine two irises with very different virtues in the hope of
getting "the best of both", then I think it makes sense to go on for
another generation or two, even if the initial seedlings aren't better than
the parents.

This is really helpful. One of the problems with figuring out what to do is that I've been breeding for 3 traits, not just two - rebloom, pretty, and reliability/survival in my growing conditions. You might think that reliability and rebloom would be the same, but they aren't. :-(

Now if I can just get more of the first generation that are fertile! I've grown a <lot> of IMM X beauty seedlings (Betty's 3rd type of cross) - most aren't fertile, most produce few surviving seedlings. But I am getting a lot of really pretty & vigorous 2nd generation seedlings from (IMM x beauty) X another beauty (Betty, you don't list this type of cross - too far from rebloom?). These seedlings combine two of the traits I'm after. Is that what you mean by going for another generation? So now it's time to make back crosses for the third trait?

My summary: if you are trying to combine very different parental traits, it
makes sense to go for another generation at least, even if the initial
seedlings fall short. If the parents are similar and you're just hoping for
improvement, and you get nothing inspiring, it might make sense to let it
go and try different crosses instead

Thanks again, Tom and Betty.

It can be a bit overwhelming...

Linda Mann east TN USA zone 7

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